Today is the second anniversary of the Chelyabinsk meteor. PBS has their NOVA episode Meteor Strike online. It gives the complete story of the event. The meteor was travelling over 40,000 mph, weighed around 13,000-14,000 tons, and measured about 20 meters in diameter. The explosion, at a height of 18 miles, had the strength of approximately 500 kilotons of TNT, which is 20-30 times larger than the atomic bomb detonated at Hiroshima. It was the largest meteor strike since the 1908 Tunguska event. The NOVA episode is very informative with discussions of meteors and what we need to do to protect the Earth.
